MIPS: SMP: Use a completion event to signal CPU up (a00eeede) · Commits · 戴 / test

If a secondary CPU failed to start, for any reason, the CPU requesting the secondary to start would get stuck in the loop waiting for the secondary to be present in the cpu_callin_map. Rather than that, use a completion event to signal that the secondary CPU has started and is waiting to synchronise counters. Since the CPU presence will no longer be marked in cpu_callin_map, remove the redundant test from arch_cpu_idle_dead(). Signed-off-by:

Matt Redfearn <matt.redfearn@imgtec.com> Cc: Maciej W. Rozycki <macro@imgtec.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Qais Yousef <qsyousef@gmail.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: Paul Burton <paul.burton@imgtec.com> Cc: Marcin Nowakowski <marcin.nowakowski@imgtec.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/14502/ Signed-off-by:

Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/process.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -50,8 +50,6 @@
		#ifdef CONFIG_HOTPLUG_CPU
		void arch_cpu_idle_dead(void)
		{
		/* What the heck is this check doing ? */
		if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
		play_dead();
		}
		#endif

arch/mips/kernel/smp.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -68,6 +68,8 @@ EXPORT_SYMBOL(cpu_sibling_map);
		cpumask_t cpu_core_map[NR_CPUS] __read_mostly;
		EXPORT_SYMBOL(cpu_core_map);

		static DECLARE_COMPLETION(cpu_running);

		/*
		* A logcal cpu mask containing only one VPE per core to
		* reduce the number of IPIs on large MT systems.
		@@ -369,7 +371,7 @@ asmlinkage void start_secondary(void)
		cpumask_set_cpu(cpu, &cpu_coherent_mask);
		notify_cpu_starting(cpu);

		cpumask_set_cpu(cpu, &cpu_callin_map);
		complete(&cpu_running);
		synchronise_count_slave(cpu);

		set_cpu_online(cpu, true);
		@@ -430,7 +432,6 @@ void smp_prepare_boot_cpu(void)
		{
		set_cpu_possible(0, true);
		set_cpu_online(0, true);
		cpumask_set_cpu(0, &cpu_callin_map);
		}

		int __cpu_up(unsigned int cpu, struct task_struct *tidle)
		@@ -438,11 +439,13 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
		mp_ops->boot_secondary(cpu, tidle);

		/*
		* Trust is futile. We should really have timeouts ...
		* We must check for timeout here, as the CPU will not be marked
		* online until the counters are synchronised.
		*/
		while (!cpumask_test_cpu(cpu, &cpu_callin_map)) {
		udelay(100);
		schedule();
		if (!wait_for_completion_timeout(&cpu_running,
		msecs_to_jiffies(1000))) {
		pr_crit("CPU%u: failed to start\n", cpu);
		return -EIO;
		}

		synchronise_count_master(cpu);

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